CALGARY – A prosecutor says first-degree murder verdicts against a man who killed a couple and their young grandson before disposing of their bodies will do little to ease the family's grief.

Douglas Garland, 57, was charged after Alvin and Kathy Liknes and five-year-old Nathan O'Brien disappeared in June 2014. He faces the possibility of spending the rest of his life in prison when he is sentenced Friday.

The victims' family wept openly as the verdicts were read. There was no reaction from Garland.

``At the end of the day, the loss of three critical people in their family ... this decision doesn't change that. They still have to grieve,'' Crown lawyer Shane Parker said Thursday.

``Victims are victims whether they're five-year-old little boys or Kathy or Alvin,'' he said. ``They're a huge loss to someone and they're a huge loss to the community as a whole.

``Who knows what Nathan would have grown up to be?''

Jurors deliberated between eight and nine hours before reaching a decision. They also recommended that Garland serve three consecutive sentences, meaning he would not be eligible for parole for 75 years.

The defence said it was too early to say whether there would be an appeal.

The couple and the boy disappeared after an estate sale at the Liknes home in Calgary. The Likneses were about to move to the Edmonton area and planned to spend their winters in Mexico. Nathan was having a sleepover with his grandparents.

When his mother arrived the next morning to pick him up, she found a house with blood pooling on the floors and spattered around rooms. A child's bloody handprint was on the wall.

Jennifer O'Brien's parents and son were missing.

The Crown argued that Garland had stewed for years over a dispute with Alvin Liknes about a patent for an oilfield pump they had both worked on. Parker also told court Garland had fantasized about Kathy Liknes as evidenced by photos of her found in Garland's deleted computer files.

The prosecution argued that the bloody state of the Liknes home showed Garland attacked the three there and that they were still alive when he took them to his Calgary-area farm where he killed them.

The victims' bodies were never recovered _ only bone fragments, burned flesh and teeth in the ash from a burning barrel on Garland's property. There was also ample DNA evidence on meat hooks and a hack saw. Garland's DNA was found on rubber boots.

Some of the 1,400 pieces of often gruesome evidence included closed-circuit security video that showed three bodies under a white tarp in the back of a truck like the one Garland drove.

An aerial photo taken on July 1, 2014, above the farm showed diaper-clad bodies of two adults and a smaller body lying near a burning barrel.

``You can still visualize Nathan curled up near grandma,'' Parker told jurors.

There was plenty of other disturbing evidence.

Jurors heard Garland had researched autopsies and the purchase of autopsy kits.

The content of a file labelled ``gore'' on his computer showed men and women wearing diapers and restrained. It included pictures of dismembered people. There were books about poisons and how to kill people.

Defence lawyer Kim Ross argued that there was no proof Garland was at the Liknes home, no way to identify him as the driver of the truck nor any proof that the three victims left the home alive.

``There's not one drop of blood. There's not one strand of hair. There's not one fingerprint. There's not one skin cell. There's no saliva. There's nothing. There's no DNA of Mr. Garland in that residence,'' Ross said during closing arguments.

The only conclusion, he said, was that Garland wasn't responsible for the deaths.

The three women and nine men on the jury disagreed.

``There's just no winners in any of this, no good way to come out of this and have a positive spin on it,'' Jim Lutz, one of Garland's other lawyers, told reporters after the verdicts.